LAN developed this three-phase master drainage plan covering over 100 square miles of contributing area, 525 miles of open channel, and 800 miles of storm sewer to guide future drainage improvements. The plan includes an assessment of open channel and closed conduit drainage systems, as well as both mature development and undeveloped areas. The plan ultimately provides guidelines for
future development in the entire City limit.

LAN developed a GIS database, designed to integrate with the InfoWorks ICM 1D/2D model to store output from the model analysis. The GIS digital inventory included the City’s digital storm sewer records, record drawings, field visits, and supplementary survey. LAN divided the City into three primary watersheds and smaller sub-watersheds for analysis efficiency, and to capture potential overland
flow or watershed overflow zones. A rapid 2D approach was piloted to define the complete workflow. The approach included the application of rainfall on the surface for the high- level analysis, with results used to establish a current baseline or level-of-service for the existing infrastructure, and to develop
understanding of the problem areas.

High priority problem areas were analyzed and incorporated into proposed improvements. Prioritization of the defined projects was based on structures removed from flooding, benefit to cost ratios, and candidacy for grants.